Author Topic: Big end bolts  (Read 1974 times)

Offline jjbsa

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Re: Big end bolts
« Reply #30 on: 27.11. 2015 22:14 »
In my recollection, the rods with castellated nuts had the washer there so that the washer could be dressed with a file to get the castellations to match a split-pin hole.

Late large journal BSA rods did vary quite a bit in the amount of clearance left for a socket spanner to tighten them (I bought numbers of these rods back in the '60s straight from BSA).  On the later rods the spanner clearance was very small and I have a socket spanner turned down to "quite thin" to undo these little so-and-sos.  28 lbs ft and red Loctite always kept them happy.  Two types of nut were fitted, firstly ones with a crimped on interference washer then the type with 2 slits in them, with the slits closed up to interfere with the bolt threads.  In the 70s and 80s there were some truly awful bolts around, I once bought some where the threads were all torn - clearly not rolled threads, and cut with a blunt die.  These went into the circular filing cabinet.  I have never seen washers fitted under self-locking nuts.

In the early 2000s I went over to the ARP bolts sold by SRM and they really are fine engineering.  Because the nuts are quite tall I had problems with their tips catching the inside of the crankcase but some filing saw to that.  I think if you want to stick to 5/16" bolts then these are the best choice.  ARP's reputation rest on their bolts!

My current motor has the billet rods made by R&R in the USA and sold by Wassell (I never thought Wassell would get into that territory!).  These are very good rods, CNC with corrugated joint faces and 3/8" x 24 ANF bolts (no nuts) made by ARP done up to something like 50 ft lbs - twice the pressure of any 5/16" bolt.